This alert expired on 3 September 2026 at 00:00 UTC. It is kept here as a record.
It is the 18th strongest of the 24 detections recorded within 20 km of this point since 14 June 2026. Another comparable one was recorded here earlier the same day.
What the source measured
NOAA reported: Flash Flood Warning issued September 2 at 3:46PM MST until September 2 at 5:00PM MST by NWS Tucson AZ
An estimated 351,094 people live within 50 km of this point.
Nearby, since 14 June 2026
- July 28, 2026 · score 39 · 12.4 km
- June 18, 2026 · score 37 · 15.5 km
- June 14, 2026 · score 43 · 15.6 km
How we know
Confirmed by 2 independent sources, including NOAA.
Our own score for this event is 37 out of 100, at 85 % confidence.
The score is ours, computed from intensity, exposed population and local history — not the source’s.
Computed under scoring rules v4. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Severe Weather |
| Severity | Medium |
| Calamity Score (ours) | 37 / 100 |
| Our confidence | 85% |
| Coordinates | 31.6600, -111.2300 |
| Nearest City | Green Valley (31 km) |
| Population Exposed | 351.1K within 50 km |
| Impact Tier | significant |
| Timestamp | 2026-09-02T22:46:00.000Z |
| Source | https://api.weather.gov/alerts/urn%3Aoid%3A2.49.0.1.840.0.e0192f4a422a691c42252529dadf09c5cfaa484b.001.1 |
Score Breakdown
Technical Details
| Event | Flash Flood Warning |
| Urgency | Immediate |
| Certainty | Likely |
| AreaDesc | Pima, AZ |
| Headline | Flash Flood Warning issued September 2 at 3:46PM MST until September 2 at 5:00PM MST by NWS Tucson AZ |
| Expires | 2026-09-02T17:00:00-07:00 |
| SenderName | NWS Tucson AZ |
| HasExactCoords | true |
| Iem TypeSummary | F |
| Iem City | 3 WNW Green Valley |
| Iem County | Pima |
| Iem State | AZ |
| Iem Wfo | TWC |
| Iem Remark | Swift Water Rescue. |
| MergedSources | [{"id":"iem_F_31.870_-111.060_1788388080000","source":"iem","severity":"low","severityValue":25,"timestamp":1788388080000,"latitude":31.87,"longitude":-111.06}] |
Safety Information
During flooding: never walk, swim, or drive through floodwaters. Six inches of moving water can knock you down, and one foot of water can sweep away a vehicle. Move to higher ground if waters rise. After flooding, avoid contact with floodwater which may contain sewage, chemicals, or debris. Follow local emergency service guidance.
Series begins 8 March 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
Want to know when something happens in this area?
Calamity.live data shows a weather event with CalamityScore 37/100 (United States), based on data from noaa. Source: Calamity.live, a platform aggregating real-time data from 185 scientific monitoring sources.